You have to be the primary member on the account or have the primary member sign a trading agreement. Box and instructions aren't required at most stores, but the guy who's buying your game needs them more than you do, so trade 'em in if you have 'em.
Deals going on now:
1. Trade in 2 games, get any new or preorder game for $30 (your trade-in value goes toward this as well)
2. Trade in 3 or more games, get an extra $5 per game
These deals work on all PS2/GC/XB/GBA/NDS games that aren't 2003 or earlier sports games, wrestling games, or Freestyle Street Soccer. Some stores let the two deals stack, some don't. Ask about stacking before you trade, because all trades are final. GR will match any published trade prices, so check other stores' trade values as well.
Your friendly neighborhood GR clerk is just trying to make a little extra money to pay for the engagement ring he bought, and this is the best job he could find that fit in with his college schedule. Please be nice to him. And if you see any unruly children messing up the games section, please kick them. Your friendly neighborhood GR clerk is not allowed to assault customers and will likely give you a free rental for allowing him to live vicariously through you.